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  <pre class="prettyprint lang-js"><span id='Ext-data-Connection'>/**
</span> * @class Ext.data.Connection
 * The Connection class encapsulates a connection to the page's originating domain, allowing requests to be made either
 * to a configured URL, or to a URL specified at request time.
 *
 * Requests made by this class are asynchronous, and will return immediately. No data from the server will be available
 * to the statement immediately following the {@link #request} call. To process returned data, use a success callback
 * in the request options object, or an {@link #requestcomplete event listener}.
 *
 * &lt;p&gt;&lt;u&gt;File Uploads&lt;/u&gt;&lt;/p&gt;
 *
 * File uploads are not performed using normal &quot;Ajax&quot; techniques, that is they are not performed using XMLHttpRequests.
 * Instead the form is submitted in the standard manner with the DOM &amp;lt;form&amp;gt; element temporarily modified to have its
 * target set to refer to a dynamically generated, hidden &amp;lt;iframe&amp;gt; which is inserted into the document but removed
 * after the return data has been gathered.
 *
 * The server response is parsed by the browser to create the document for the IFRAME. If the server is using JSON to
 * send the return object, then the Content-Type header must be set to &quot;text/html&quot; in order to tell the browser to
 * insert the text unchanged into the document body.
 *
 * Characters which are significant to an HTML parser must be sent as HTML entities, so encode &quot;&amp;lt;&quot; as &quot;&amp;amp;lt;&quot;, &quot;&amp;amp;&quot; as
 * &quot;&amp;amp;amp;&quot; etc.
 *
 * The response text is retrieved from the document, and a fake XMLHttpRequest object is created containing a
 * responseText property in order to conform to the requirements of event handlers and callbacks.
 *
 * Be aware that file upload packets are sent with the content type multipart/form and some server technologies
 * (notably JEE) may require some custom processing in order to retrieve parameter names and parameter values from the
 * packet content.
 *
 * Also note that it's not possible to check the response code of the hidden iframe, so the success handler will ALWAYS fire.
 */
Ext.define('Ext.data.Connection', {
    mixins: {
        observable: 'Ext.util.Observable'
    },

    statics: {
        requestId: 0
    },

    url: null,
    async: true,
    method: null,
    username: '',
    password: '',

<span id='Ext-data-Connection-cfg-disableCaching'>    /**
</span>     * @cfg {Boolean} disableCaching (Optional) True to add a unique cache-buster param to GET requests. (defaults to true)
     */
    disableCaching: true,

<span id='Ext-data-Connection-cfg-disableCachingParam'>    /**
</span>     * @cfg {String} disableCachingParam (Optional) Change the parameter which is sent went disabling caching
     * through a cache buster. Defaults to '_dc'
     */
    disableCachingParam: '_dc',

<span id='Ext-data-Connection-cfg-timeout'>    /**
</span>     * @cfg {Number} timeout (Optional) The timeout in milliseconds to be used for requests. (defaults to 30000)
     */
    timeout : 30000,

<span id='Ext-data-Connection-cfg-extraParams'>    /**
</span>     * @cfg {Object} extraParams (Optional) Any parameters to be appended to the request.
     */

    useDefaultHeader : true,
    defaultPostHeader : 'application/x-www-form-urlencoded; charset=UTF-8',
    useDefaultXhrHeader : true,
    defaultXhrHeader : 'XMLHttpRequest',

    constructor : function(config) {
        config = config || {};
        Ext.apply(this, config);

        this.addEvents(
<span id='Ext-data-Connection-event-beforerequest'>            /**
</span>             * @event beforerequest
             * Fires before a network request is made to retrieve a data object.
             * @param {Connection} conn This Connection object.
             * @param {Object} options The options config object passed to the {@link #request} method.
             */
            'beforerequest',
<span id='Ext-data-Connection-event-requestcomplete'>            /**
</span>             * @event requestcomplete
             * Fires if the request was successfully completed.
             * @param {Connection} conn This Connection object.
             * @param {Object} response The XHR object containing the response data.
             * See &lt;a href=&quot;http://www.w3.org/TR/XMLHttpRequest/&quot;&gt;The XMLHttpRequest Object&lt;/a&gt;
             * for details.
             * @param {Object} options The options config object passed to the {@link #request} method.
             */
            'requestcomplete',
<span id='Ext-data-Connection-event-requestexception'>            /**
</span>             * @event requestexception
             * Fires if an error HTTP status was returned from the server.
             * See &lt;a href=&quot;http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html&quot;&gt;HTTP Status Code Definitions&lt;/a&gt;
             * for details of HTTP status codes.
             * @param {Connection} conn This Connection object.
             * @param {Object} response The XHR object containing the response data.
             * See &lt;a href=&quot;http://www.w3.org/TR/XMLHttpRequest/&quot;&gt;The XMLHttpRequest Object&lt;/a&gt;
             * for details.
             * @param {Object} options The options config object passed to the {@link #request} method.
             */
            'requestexception'
        );
        this.requests = {};
        this.mixins.observable.constructor.call(this);
    },

<span id='Ext-data-Connection-method-request'>    /**
</span>     * &lt;p&gt;Sends an HTTP request to a remote server.&lt;/p&gt;
     * &lt;p&gt;&lt;b&gt;Important:&lt;/b&gt; Ajax server requests are asynchronous, and this call will
     * return before the response has been received. Process any returned data
     * in a callback function.&lt;/p&gt;
     * &lt;pre&gt;&lt;code&gt;
Ext.Ajax.request({
url: 'ajax_demo/sample.json',
success: function(response, opts) {
  var obj = Ext.decode(response.responseText);
  console.dir(obj);
},
failure: function(response, opts) {
  console.log('server-side failure with status code ' + response.status);
}
});
     * &lt;/code&gt;&lt;/pre&gt;
     * &lt;p&gt;To execute a callback function in the correct scope, use the &lt;tt&gt;scope&lt;/tt&gt; option.&lt;/p&gt;
     * @param {Object} options An object which may contain the following properties:&lt;ul&gt;
     * &lt;li&gt;&lt;b&gt;url&lt;/b&gt; : String/Function (Optional)&lt;div class=&quot;sub-desc&quot;&gt;The URL to
     * which to send the request, or a function to call which returns a URL string. The scope of the
     * function is specified by the &lt;tt&gt;scope&lt;/tt&gt; option. Defaults to the configured
     * &lt;tt&gt;{@link #url}&lt;/tt&gt;.&lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;b&gt;params&lt;/b&gt; : Object/String/Function (Optional)&lt;div class=&quot;sub-desc&quot;&gt;
     * An object containing properties which are used as parameters to the
     * request, a url encoded string or a function to call to get either. The scope of the function
     * is specified by the &lt;tt&gt;scope&lt;/tt&gt; option.&lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;b&gt;method&lt;/b&gt; : String (Optional)&lt;div class=&quot;sub-desc&quot;&gt;The HTTP method to use
     * for the request. Defaults to the configured method, or if no method was configured,
     * &quot;GET&quot; if no parameters are being sent, and &quot;POST&quot; if parameters are being sent.  Note that
     * the method name is case-sensitive and should be all caps.&lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;b&gt;callback&lt;/b&gt; : Function (Optional)&lt;div class=&quot;sub-desc&quot;&gt;The
     * function to be called upon receipt of the HTTP response. The callback is
     * called regardless of success or failure and is passed the following
     * parameters:&lt;ul&gt;
     * &lt;li&gt;&lt;b&gt;options&lt;/b&gt; : Object&lt;div class=&quot;sub-desc&quot;&gt;The parameter to the request call.&lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;b&gt;success&lt;/b&gt; : Boolean&lt;div class=&quot;sub-desc&quot;&gt;True if the request succeeded.&lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;b&gt;response&lt;/b&gt; : Object&lt;div class=&quot;sub-desc&quot;&gt;The XMLHttpRequest object containing the response data.
     * See &lt;a href=&quot;http://www.w3.org/TR/XMLHttpRequest/&quot;&gt;http://www.w3.org/TR/XMLHttpRequest/&lt;/a&gt; for details about
     * accessing elements of the response.&lt;/div&gt;&lt;/li&gt;
     * &lt;/ul&gt;&lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;a id=&quot;request-option-success&quot;&gt;&lt;/a&gt;&lt;b&gt;success&lt;/b&gt; : Function (Optional)&lt;div class=&quot;sub-desc&quot;&gt;The function
     * to be called upon success of the request. The callback is passed the following
     * parameters:&lt;ul&gt;
     * &lt;li&gt;&lt;b&gt;response&lt;/b&gt; : Object&lt;div class=&quot;sub-desc&quot;&gt;The XMLHttpRequest object containing the response data.&lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;b&gt;options&lt;/b&gt; : Object&lt;div class=&quot;sub-desc&quot;&gt;The parameter to the request call.&lt;/div&gt;&lt;/li&gt;
     * &lt;/ul&gt;&lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;b&gt;failure&lt;/b&gt; : Function (Optional)&lt;div class=&quot;sub-desc&quot;&gt;The function
     * to be called upon failure of the request. The callback is passed the
     * following parameters:&lt;ul&gt;
     * &lt;li&gt;&lt;b&gt;response&lt;/b&gt; : Object&lt;div class=&quot;sub-desc&quot;&gt;The XMLHttpRequest object containing the response data.&lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;b&gt;options&lt;/b&gt; : Object&lt;div class=&quot;sub-desc&quot;&gt;The parameter to the request call.&lt;/div&gt;&lt;/li&gt;
     * &lt;/ul&gt;&lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;b&gt;scope&lt;/b&gt; : Object (Optional)&lt;div class=&quot;sub-desc&quot;&gt;The scope in
     * which to execute the callbacks: The &quot;this&quot; object for the callback function. If the &lt;tt&gt;url&lt;/tt&gt;, or &lt;tt&gt;params&lt;/tt&gt; options were
     * specified as functions from which to draw values, then this also serves as the scope for those function calls.
     * Defaults to the browser window.&lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;b&gt;timeout&lt;/b&gt; : Number (Optional)&lt;div class=&quot;sub-desc&quot;&gt;The timeout in milliseconds to be used for this request. Defaults to 30 seconds.&lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;b&gt;form&lt;/b&gt; : Element/HTMLElement/String (Optional)&lt;div class=&quot;sub-desc&quot;&gt;The &lt;tt&gt;&amp;lt;form&amp;gt;&lt;/tt&gt;
     * Element or the id of the &lt;tt&gt;&amp;lt;form&amp;gt;&lt;/tt&gt; to pull parameters from.&lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;a id=&quot;request-option-isUpload&quot;&gt;&lt;/a&gt;&lt;b&gt;isUpload&lt;/b&gt; : Boolean (Optional)&lt;div class=&quot;sub-desc&quot;&gt;&lt;b&gt;Only meaningful when used
     * with the &lt;tt&gt;form&lt;/tt&gt; option&lt;/b&gt;.
     * &lt;p&gt;True if the form object is a file upload (will be set automatically if the form was
     * configured with &lt;b&gt;&lt;tt&gt;enctype&lt;/tt&gt;&lt;/b&gt; &quot;multipart/form-data&quot;).&lt;/p&gt;
     * &lt;p&gt;File uploads are not performed using normal &quot;Ajax&quot; techniques, that is they are &lt;b&gt;not&lt;/b&gt;
     * performed using XMLHttpRequests. Instead the form is submitted in the standard manner with the
     * DOM &lt;tt&gt;&amp;lt;form&gt;&lt;/tt&gt; element temporarily modified to have its
     * &lt;a href=&quot;http://www.w3.org/TR/REC-html40/present/frames.html#adef-target&quot;&gt;target&lt;/a&gt; set to refer
     * to a dynamically generated, hidden &lt;tt&gt;&amp;lt;iframe&gt;&lt;/tt&gt; which is inserted into the document
     * but removed after the return data has been gathered.&lt;/p&gt;
     * &lt;p&gt;The server response is parsed by the browser to create the document for the IFRAME. If the
     * server is using JSON to send the return object, then the
     * &lt;a href=&quot;http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.17&quot;&gt;Content-Type&lt;/a&gt; header
     * must be set to &quot;text/html&quot; in order to tell the browser to insert the text unchanged into the document body.&lt;/p&gt;
     * &lt;p&gt;The response text is retrieved from the document, and a fake XMLHttpRequest object
     * is created containing a &lt;tt&gt;responseText&lt;/tt&gt; property in order to conform to the
     * requirements of event handlers and callbacks.&lt;/p&gt;
     * &lt;p&gt;Be aware that file upload packets are sent with the content type &lt;a href=&quot;http://www.faqs.org/rfcs/rfc2388.html&quot;&gt;multipart/form&lt;/a&gt;
     * and some server technologies (notably JEE) may require some custom processing in order to
     * retrieve parameter names and parameter values from the packet content.&lt;/p&gt;
     * &lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;b&gt;headers&lt;/b&gt; : Object (Optional)&lt;div class=&quot;sub-desc&quot;&gt;Request
     * headers to set for the request.&lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;b&gt;xmlData&lt;/b&gt; : Object (Optional)&lt;div class=&quot;sub-desc&quot;&gt;XML document
     * to use for the post. Note: This will be used instead of params for the post
     * data. Any params will be appended to the URL.&lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;b&gt;jsonData&lt;/b&gt; : Object/String (Optional)&lt;div class=&quot;sub-desc&quot;&gt;JSON
     * data to use as the post. Note: This will be used instead of params for the post
     * data. Any params will be appended to the URL.&lt;/div&gt;&lt;/li&gt;
     * &lt;li&gt;&lt;b&gt;disableCaching&lt;/b&gt; : Boolean (Optional)&lt;div class=&quot;sub-desc&quot;&gt;True
     * to add a unique cache-buster param to GET requests.&lt;/div&gt;&lt;/li&gt;
     * &lt;/ul&gt;&lt;/p&gt;
     * &lt;p&gt;The options object may also contain any other property which might be needed to perform
     * postprocessing in a callback because it is passed to callback functions.&lt;/p&gt;
     * @return {Object} request The request object. This may be used
     * to cancel the request.
     */
    request : function(options) {
        options = options || {};
        var me = this,
            scope = options.scope || window,
            username = options.username || me.username,
            password = options.password || me.password || '',
            async,
            requestOptions,
            request,
            headers,
            xhr;

        if (me.fireEvent('beforerequest', me, options) !== false) {

            requestOptions = me.setOptions(options, scope);

            if (this.isFormUpload(options) === true) {
                this.upload(options.form, requestOptions.url, requestOptions.data, options);
                return null;
            }

            // if autoabort is set, cancel the current transactions
            if (options.autoAbort === true || me.autoAbort) {
                me.abort();
            }

            // create a connection object
            xhr = this.getXhrInstance();

            async = options.async !== false ? (options.async || me.async) : false;

            // open the request
            if (username) {
                xhr.open(requestOptions.method, requestOptions.url, async, username, password);
            } else {
                xhr.open(requestOptions.method, requestOptions.url, async);
            }

            headers = me.setupHeaders(xhr, options, requestOptions.data, requestOptions.params);

            // create the transaction object
            request = {
                id: ++Ext.data.Connection.requestId,
                xhr: xhr,
                headers: headers,
                options: options,
                async: async,
                timeout: setTimeout(function() {
                    request.timedout = true;
                    me.abort(request);
                }, options.timeout || me.timeout)
            };
            me.requests[request.id] = request;

            // bind our statechange listener
            if (async) {
                xhr.onreadystatechange = Ext.Function.bind(me.onStateChange, me, [request]);
            }

            // start the request!
            xhr.send(requestOptions.data);
            if (!async) {
                return this.onComplete(request);
            }
            return request;
        } else {
            Ext.callback(options.callback, options.scope, [options, undefined, undefined]);
            return null;
        }
    },

<span id='Ext-data-Connection-method-upload'>    /**
</span>     * Upload a form using a hidden iframe.
     * @param {Mixed} form The form to upload
     * @param {String} url The url to post to
     * @param {String} params Any extra parameters to pass
     * @param {Object} options The initial options
     */
    upload: function(form, url, params, options){
        form = Ext.getDom(form);
        options = options || {};

        var id = Ext.id(),
                frame = document.createElement('iframe'),
                hiddens = [],
                encoding = 'multipart/form-data',
                buf = {
                    target: form.target,
                    method: form.method,
                    encoding: form.encoding,
                    enctype: form.enctype,
                    action: form.action
                }, hiddenItem;

        /*
         * Originally this behaviour was modified for Opera 10 to apply the secure URL after
         * the frame had been added to the document. It seems this has since been corrected in
         * Opera so the behaviour has been reverted, the URL will be set before being added.
         */
        Ext.fly(frame).set({
            id: id,
            name: id,
            cls: Ext.baseCSSPrefix + 'hide-display',
            src: Ext.SSL_SECURE_URL
        });

        document.body.appendChild(frame);

        // This is required so that IE doesn't pop the response up in a new window.
        if (document.frames) {
           document.frames[id].name = id;
        }

        Ext.fly(form).set({
            target: id,
            method: 'POST',
            enctype: encoding,
            encoding: encoding,
            action: url || buf.action
        });

        // add dynamic params
        if (params) {
            Ext.iterate(Ext.Object.fromQueryString(params), function(name, value){
                hiddenItem = document.createElement('input');
                Ext.fly(hiddenItem).set({
                    type: 'hidden',
                    value: value,
                    name: name
                });
                form.appendChild(hiddenItem);
                hiddens.push(hiddenItem);
            });
        }

        Ext.fly(frame).on('load', Ext.Function.bind(this.onUploadComplete, this, [frame, options]), null, {single: true});
        form.submit();

        Ext.fly(form).set(buf);
        Ext.each(hiddens, function(h) {
            Ext.removeNode(h);
        });
    },

    onUploadComplete: function(frame, options){
        var me = this,
            // bogus response object
            response = {
                responseText: '',
                responseXML: null
            }, doc, firstChild;

        try {
            doc = frame.contentWindow.document || frame.contentDocument || window.frames[id].document;
            if (doc) {
                if (doc.body) {
                    if (/textarea/i.test((firstChild = doc.body.firstChild || {}).tagName)) { // json response wrapped in textarea
                        response.responseText = firstChild.value;
                    } else {
                        response.responseText = doc.body.innerHTML;
                    }
                }
                //in IE the document may still have a body even if returns XML.
                response.responseXML = doc.XMLDocument || doc;
            }
        } catch (e) {
        }

        me.fireEvent('requestcomplete', me, response, options);

        Ext.callback(options.success, options.scope, [response, options]);
        Ext.callback(options.callback, options.scope, [options, true, response]);

        setTimeout(function(){
            Ext.removeNode(frame);
        }, 100);
    },

<span id='Ext-data-Connection-method-isFormUpload'>    /**
</span>     * Detect whether the form is intended to be used for an upload.
     * @private
     */
    isFormUpload: function(options){
        var form = this.getForm(options);
        if (form) {
            return (options.isUpload || (/multipart\/form-data/i).test(form.getAttribute('enctype')));
        }
        return false;
    },

<span id='Ext-data-Connection-method-getForm'>    /**
</span>     * Get the form object from options.
     * @private
     * @param {Object} options The request options
     * @return {HTMLElement} The form, null if not passed
     */
    getForm: function(options){
        return Ext.getDom(options.form) || null;
    },

<span id='Ext-data-Connection-method-setOptions'>    /**
</span>     * Set various options such as the url, params for the request
     * @param {Object} options The initial options
     * @param {Object} scope The scope to execute in
     * @return {Object} The params for the request
     */
    setOptions: function(options, scope){
        var me =  this,
            params = options.params || {},
            extraParams = me.extraParams,
            urlParams = options.urlParams,
            url = options.url || me.url,
            jsonData = options.jsonData,
            method,
            disableCache,
            data;


        // allow params to be a method that returns the params object
        if (Ext.isFunction(params)) {
            params = params.call(scope, options);
        }

        // allow url to be a method that returns the actual url
        if (Ext.isFunction(url)) {
            url = url.call(scope, options);
        }

        url = this.setupUrl(options, url);

        //&lt;debug&gt;
        if (!url) {
            Ext.Error.raise({
                options: options,
                msg: 'No URL specified'
            });
        }
        //&lt;/debug&gt;

        // check for xml or json data, and make sure json data is encoded
        data = options.rawData || options.xmlData || jsonData || null;
        if (jsonData &amp;&amp; !Ext.isPrimitive(jsonData)) {
            data = Ext.encode(data);
        }

        // make sure params are a url encoded string and include any extraParams if specified
        if (Ext.isObject(params)) {
            params = Ext.Object.toQueryString(params);
        }

        if (Ext.isObject(extraParams)) {
            extraParams = Ext.Object.toQueryString(extraParams);
        }

        params = params + ((extraParams) ? ((params) ? '&amp;' : '') + extraParams : '');

        urlParams = Ext.isObject(urlParams) ? Ext.Object.toQueryString(urlParams) : urlParams;

        params = this.setupParams(options, params);

        // decide the proper method for this request
        method = (options.method || me.method || ((params || data) ? 'POST' : 'GET')).toUpperCase();
        this.setupMethod(options, method);


        disableCache = options.disableCaching !== false ? (options.disableCaching || me.disableCaching) : false;
        // if the method is get append date to prevent caching
        if (method === 'GET' &amp;&amp; disableCache) {
            url = Ext.urlAppend(url, (options.disableCachingParam || me.disableCachingParam) + '=' + (new Date().getTime()));
        }

        // if the method is get or there is json/xml data append the params to the url
        if ((method == 'GET' || data) &amp;&amp; params) {
            url = Ext.urlAppend(url, params);
            params = null;
        }

        // allow params to be forced into the url
        if (urlParams) {
            url = Ext.urlAppend(url, urlParams);
        }

        return {
            url: url,
            method: method,
            data: data || params || null
        };
    },

<span id='Ext-data-Connection-method-setupUrl'>    /**
</span>     * Template method for overriding url
     * @private
     * @param {Object} options
     * @param {String} url
     * @return {String} The modified url
     */
    setupUrl: function(options, url){
        var form = this.getForm(options);
        if (form) {
            url = url || form.action;
        }
        return url;
    },


<span id='Ext-data-Connection-method-setupParams'>    /**
</span>     * Template method for overriding params
     * @private
     * @param {Object} options
     * @param {String} params
     * @return {String} The modified params
     */
    setupParams: function(options, params) {
        var form = this.getForm(options),
            serializedForm;
        if (form &amp;&amp; !this.isFormUpload(options)) {
            serializedForm = Ext.core.Element.serializeForm(form);
            params = params ? (params + '&amp;' + serializedForm) : serializedForm;
        }
        return params;
    },

<span id='Ext-data-Connection-method-setupMethod'>    /**
</span>     * Template method for overriding method
     * @private
     * @param {Object} options
     * @param {String} method
     * @return {String} The modified method
     */
    setupMethod: function(options, method){
        if (this.isFormUpload(options)) {
            return 'POST';
        }
        return method;
    },

<span id='Ext-data-Connection-method-setupHeaders'>    /**
</span>     * Setup all the headers for the request
     * @private
     * @param {Object} xhr The xhr object
     * @param {Object} options The options for the request
     * @param {Object} data The data for the request
     * @param {Object} params The params for the request
     */
    setupHeaders: function(xhr, options, data, params){
        var me = this,
            headers = Ext.apply({}, options.headers || {}, me.defaultHeaders || {}),
            contentType = me.defaultPostHeader,
            jsonData = options.jsonData,
            xmlData = options.xmlData,
            key,
            header;

        if (!headers['Content-Type'] &amp;&amp; (data || params)) {
            if (data) {
                if (options.rawData) {
                    contentType = 'text/plain';
                } else {
                    if (xmlData &amp;&amp; Ext.isDefined(xmlData)) {
                        contentType = 'text/xml';
                    } else if (jsonData &amp;&amp; Ext.isDefined(jsonData)) {
                        contentType = 'application/json';
                    }
                }
            }
            headers['Content-Type'] = contentType;
        }

        if (me.useDefaultXhrHeader &amp;&amp; !headers['X-Requested-With']) {
            headers['X-Requested-With'] = me.defaultXhrHeader;
        }
        // set up all the request headers on the xhr object
        try{
            for (key in headers) {
                if (headers.hasOwnProperty(key)) {
                    header = headers[key];
                    xhr.setRequestHeader(key, header);
                }

            }
        } catch(e) {
            me.fireEvent('exception', key, header);
        }
        return headers;
    },

<span id='Ext-data-Connection-property-getXhrInstance'>    /**
</span>     * Creates the appropriate XHR transport for the browser.
     * @private
     */
    getXhrInstance: (function(){
        var options = [function(){
            return new XMLHttpRequest();
        }, function(){
            return new ActiveXObject('MSXML2.XMLHTTP.3.0');
        }, function(){
            return new ActiveXObject('MSXML2.XMLHTTP');
        }, function(){
            return new ActiveXObject('Microsoft.XMLHTTP');
        }], i = 0,
            len = options.length,
            xhr;

        for(; i &lt; len; ++i) {
            try{
                xhr = options[i];
                xhr();
                break;
            }catch(e){}
        }
        return xhr;
    })(),

<span id='Ext-data-Connection-method-isLoading'>    /**
</span>     * Determine whether this object has a request outstanding.
     * @param {Object} request (Optional) defaults to the last transaction
     * @return {Boolean} True if there is an outstanding request.
     */
    isLoading : function(request) {
        if (!(request &amp;&amp; request.xhr)) {
            return false;
        }
        // if there is a connection and readyState is not 0 or 4
        var state = request.xhr.readyState;
        return !(state === 0 || state == 4);
    },

<span id='Ext-data-Connection-method-abort'>    /**
</span>     * Aborts any outstanding request.
     * @param {Object} request (Optional) defaults to the last request
     */
    abort : function(request) {
        var me = this,
            requests = me.requests,
            id;

        if (request &amp;&amp; me.isLoading(request)) {
            /*
             * Clear out the onreadystatechange here, this allows us
             * greater control, the browser may/may not fire the function
             * depending on a series of conditions.
             */
            request.xhr.onreadystatechange = null;
            request.xhr.abort();
            me.clearTimeout(request);
            if (!request.timedout) {
                request.aborted = true;
            }
            me.onComplete(request);
            me.cleanup(request);
        } else if (!request) {
            for(id in requests) {
                if (requests.hasOwnProperty(id)) {
                    me.abort(requests[id]);
                }
            }
        }
    },

<span id='Ext-data-Connection-method-onStateChange'>    /**
</span>     * Fires when the state of the xhr changes
     * @private
     * @param {Object} request The request
     */
    onStateChange : function(request) {
        if (request.xhr.readyState == 4) {
            this.clearTimeout(request);
            this.onComplete(request);
            this.cleanup(request);
        }
    },

<span id='Ext-data-Connection-method-clearTimeout'>    /**
</span>     * Clear the timeout on the request
     * @private
     * @param {Object} The request
     */
    clearTimeout: function(request){
        clearTimeout(request.timeout);
        delete request.timeout;
    },

<span id='Ext-data-Connection-method-cleanup'>    /**
</span>     * Clean up any left over information from the request
     * @private
     * @param {Object} The request
     */
    cleanup: function(request){
        request.xhr = null;
        delete request.xhr;
    },

<span id='Ext-data-Connection-method-onComplete'>    /**
</span>     * To be called when the request has come back from the server
     * @private
     * @param {Object} request
     * @return {Object} The response
     */
    onComplete : function(request) {
        var me = this,
            options = request.options,
            result,
            success,
            response;
            
        try {
            result = me.parseStatus(request.xhr.status);
        } catch (e) {
            // in some browsers we can't access the status if the readyState is not 4, so the request has failed
            result = {
                success : false, 
                isException : false 
            };
        }
        success = result.success;

        if (success) {
            response = me.createResponse(request);
            me.fireEvent('requestcomplete', me, response, options);
            Ext.callback(options.success, options.scope, [response, options]);
        } else {
            if (result.isException || request.aborted || request.timedout) {
                response = me.createException(request);
            } else {
                response = me.createResponse(request);
            }
            me.fireEvent('requestexception', me, response, options);
            Ext.callback(options.failure, options.scope, [response, options]);
        }
        Ext.callback(options.callback, options.scope, [options, success, response]);
        delete me.requests[request.id];
        return response;
    },

<span id='Ext-data-Connection-method-parseStatus'>    /**
</span>     * Check if the response status was successful
     * @param {Number} status The status code
     * @return {Object} An object containing success/status state
     */
    parseStatus: function(status) {
        // see: https://prototype.lighthouseapp.com/projects/8886/tickets/129-ie-mangles-http-response-status-code-204-to-1223
        status = status == 1223 ? 204 : status;

        var success = (status &gt;= 200 &amp;&amp; status &lt; 300) || status == 304,
            isException = false;

        if (!success) {
            switch (status) {
                case 12002:
                case 12029:
                case 12030:
                case 12031:
                case 12152:
                case 13030:
                    isException = true;
                    break;
            }
        }
        return {
            success: success,
            isException: isException
        };
    },

<span id='Ext-data-Connection-method-createResponse'>    /**
</span>     * Create the response object
     * @private
     * @param {Object} request
     */
    createResponse : function(request) {
        var xhr = request.xhr,
            headers = {},
            lines = xhr.getAllResponseHeaders().replace(/\r\n/g, '\n').split('\n'),
            count = lines.length,
            line, index, key, value, response;

        while (count--) {
            line = lines[count];
            index = line.indexOf(':');
            if(index &gt;= 0) {
                key = line.substr(0, index).toLowerCase();
                if (line.charAt(index + 1) == ' ') {
                    ++index;
                }
                headers[key] = line.substr(index + 1);
            }
        }

        request.xhr = null;
        delete request.xhr;

        response = {
            request: request,
            requestId : request.id,
            status : xhr.status,
            statusText : xhr.statusText,
            getResponseHeader : function(header){ return headers[header.toLowerCase()]; },
            getAllResponseHeaders : function(){ return headers; },
            responseText : xhr.responseText,
            responseXML : xhr.responseXML
        };

        // If we don't explicitly tear down the xhr reference, IE6/IE7 will hold this in the closure of the
        // functions created with getResponseHeader/getAllResponseHeaders
        xhr = null;
        return response;
    },

<span id='Ext-data-Connection-method-createException'>    /**
</span>     * Create the exception object
     * @private
     * @param {Object} request
     */
    createException : function(request) {
        return {
            request : request,
            requestId : request.id,
            status : request.aborted ? -1 : 0,
            statusText : request.aborted ? 'transaction aborted' : 'communication failure',
            aborted: request.aborted,
            timedout: request.timedout
        };
    }
});
</pre>
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